/*
 * Copyright 2002-2006 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package org.springframework.jtracc.util;

import java.util.Collection;
import java.util.Map;

/**
 * Assert utility class that assists in validating arguments. Useful for
 * identifying programmer errors early and obviously at runtime.
 * <p/>
 * <p>For example, if the contract of a public method states it does not
 * allow <code>null</code> arguments, Assert can be used to validate that
 * contract. Doing this clearly indicates a contract violation when it
 * occurs and protects the class's invariants.
 * <p/>
 * <p>Typically used to validate method arguments rather than configuration
 * properties, to check for cases that are usually programmer errors rather than
 * configuration errors. In contrast to config initialization code, there is
 * usally no point in falling back to defaults in such methods.
 * <p/>
 * <p>This class is similar to JUnit's assertion library. If an argument value is
 * deemed invalid, an {@link IllegalArgumentException} is thrown (typically).
 * For example:
 * <p/>
 * <pre class="code">
 * Assert.notNull(clazz, "The class must not be null");
 * Assert.isTrue(i > 0, "The value must be greater than zero");</pre>
 * <p/>
 * Mainly for internal use within the framework; consider Jakarta's Commons Lang
 * >= 2.0 for a more comprehensive suite of assertion utilities.
 *
 * @author Keith Donald
 * @author Juergen Hoeller
 * @author Colin Sampaleanu
 * @author Rob Harrop
 * @author Erwin Vervaet
 * @since 1.1.2
 */
public abstract class Assert
{

    /**
     * Assert a boolean expression, throwing <code>IllegalArgumentException</code>
     * if the test result is <code>false</code>.
     * <pre class="code">Assert.isTrue(i &gt; 0, "The value must be greater than zero");</pre>
     *
     * @param expression a boolean expression
     * @param message    the exception message to use if the assertion fails
     *
     * @throws IllegalArgumentException if expression is <code>false</code>
     */
    public static void isTrue(boolean expression, String message)
    {
        if (!expression)
        {
            throw new IllegalArgumentException( message );
        }
    }

    /**
     * Assert a boolean expression, throwing <code>IllegalArgumentException</code>
     * if the test result is <code>false</code>.
     * <pre class="code">Assert.isTrue(i &gt; 0);</pre>
     *
     * @param expression a boolean expression
     *
     * @throws IllegalArgumentException if expression is <code>false</code>
     */
    public static void isTrue(boolean expression)
    {
        isTrue( expression, "[Assertion failed] - this expression must be true" );
    }

    /**
     * Assert that an object is <code>null</code> .
     * <pre class="code">Assert.isNull(value, "The value must be null");</pre>
     *
     * @param object  the object to check
     * @param message the exception message to use if the assertion fails
     *
     * @throws IllegalArgumentException if the object is not <code>null</code>
     */
    public static void isNull(Object object, String message)
    {
        if (object != null)
        {
            throw new IllegalArgumentException( message );
        }
    }

    /**
     * Assert that an object is <code>null</code> .
     * <pre class="code">Assert.isNull(value);</pre>
     *
     * @param object the object to check
     *
     * @throws IllegalArgumentException if the object is not <code>null</code>
     */
    public static void isNull(Object object)
    {
        isNull( object, "[Assertion failed] - the object argument must be null" );
    }

    /**
     * Assert that an object is not <code>null</code> .
     * <pre class="code">Assert.notNull(clazz, "The class must not be null");</pre>
     *
     * @param object  the object to check
     * @param message the exception message to use if the assertion fails
     *
     * @throws IllegalArgumentException if the object is <code>null</code>
     */
    public static void notNull(Object object, String message)
    {
        if (object == null)
        {
            throw new IllegalArgumentException( message );
        }
    }

    /**
     * Assert that an object is not <code>null</code> .
     * <pre class="code">Assert.notNull(clazz);</pre>
     *
     * @param object the object to check
     *
     * @throws IllegalArgumentException if the object is <code>null</code>
     */
    public static void notNull(Object object)
    {
        notNull( object, "[Assertion failed] - this argument is required; it cannot be null" );
    }

    /**
     * Assert that a string is not empty; that is, it must not be <code>null</code> and not empty.
     * <pre class="code">Assert.hasLength(name, "Name must not be empty");</pre>
     *
     * @param text    the string to check
     * @param message the exception message to use if the assertion fails
     *
     * @see StringUtils#hasLength
     */
    public static void hasLength(String text, String message)
    {
        if (!StringUtils.hasLength( text ))
        {
            throw new IllegalArgumentException( message );
        }
    }

    /**
     * Assert that a string is not empty; that is, it must not be <code>null</code> and not empty.
     * <pre class="code">Assert.hasLength(name);</pre>
     *
     * @param text the string to check
     *
     * @see StringUtils#hasLength
     */
    public static void hasLength(String text)
    {
        hasLength( text,
                   "[Assertion failed] - this String argument must have length; it cannot be <code>null</code> or empty" );
    }

    /**
     * Assert that a string has valid text content; that is, it must not be <code>null</code>
     * and must contain at least one non-whitespace character.
     * <pre class="code">Assert.hasText(name, "Name must not be empty");</pre>
     *
     * @param text    the string to check
     * @param message the exception message to use if the assertion fails
     *
     * @see StringUtils#hasText
     */
    public static void hasText(String text, String message)
    {
        if (!StringUtils.hasText( text ))
        {
            throw new IllegalArgumentException( message );
        }
    }

    /**
     * Assert that a string has valid text content; that is, it must not be <code>null</code>
     * and must contain at least one non-whitespace character.
     * <pre class="code">Assert.hasText(name, "Name must not be empty");</pre>
     *
     * @param text the string to check
     *
     * @see StringUtils#hasText
     */
    public static void hasText(String text)
    {
        hasText( text,
                 "[Assertion failed] - this String argument must have text; it cannot be <code>null</code>, empty, or blank" );
    }

    /**
     * Assert that the given text does not contain the given substring.
     * <pre class="code">Assert.doesNotContain(name, "rod", "Name must not contain 'rod'");</pre>
     *
     * @param textToSearch the text to search
     * @param substring    the substring to find within the text
     * @param message      the exception message to use if the assertion fails
     */
    public static void doesNotContain(String textToSearch, String substring, String message)
    {
        if (StringUtils.hasLength( textToSearch ) && StringUtils.hasLength( substring ) &&
            textToSearch.indexOf( substring ) != -1)
        {
            throw new IllegalArgumentException( message );
        }
    }

    /**
     * Assert that the given text does not contain the given substring.
     * <pre class="code">Assert.doesNotContain(name, "rod");</pre>
     *
     * @param textToSearch the text to search
     * @param substring    the substring to find within the text
     */
    public static void doesNotContain(String textToSearch, String substring)
    {
        doesNotContain( textToSearch, substring,
                        "[Assertion failed] - this String argument must not contain the substring [" + substring + "]" );
    }


    /**
     * Assert that an array has elements; that is, it must not be
     * <code>null</code> and must have at least one element.
     * <pre class="code">Assert.notEmpty(array, "The array must have elements");</pre>
     *
     * @param array   the array to check
     * @param message the exception message to use if the assertion fails
     *
     * @throws IllegalArgumentException if the object array is <code>null</code> or has no elements
     */
    public static void notEmpty(Object[] array, String message)
    {
        if (ObjectUtils.isEmpty( array ))
        {
            throw new IllegalArgumentException( message );
        }
    }

    /**
     * Assert that an array has elements; that is, it must not be
     * <code>null</code> and must have at least one element.
     * <pre class="code">Assert.notEmpty(array);</pre>
     *
     * @param array the array to check
     *
     * @throws IllegalArgumentException if the object array is <code>null</code> or has no elements
     */
    public static void notEmpty(Object[] array)
    {
        notEmpty( array, "[Assertion failed] - this array must not be empty: it must contain at least 1 element" );
    }

    /**
     * Assert that a collection has elements; that is, it must not be
     * <code>null</code> and must have at least one element.
     * <pre class="code">Assert.notEmpty(collection, "Collection must have elements");</pre>
     *
     * @param collection the collection to check
     * @param message    the exception message to use if the assertion fails
     *
     * @throws IllegalArgumentException if the collection is <code>null</code> or has no elements
     */
    public static void notEmpty(Collection collection, String message)
    {
        if (CollectionUtils.isEmpty( collection ))
        {
            throw new IllegalArgumentException( message );
        }
    }

    /**
     * Assert that a collection has elements; that is, it must not be
     * <code>null</code> and must have at least one element.
     * <pre class="code">Assert.notEmpty(collection, "Collection must have elements");</pre>
     *
     * @param collection the collection to check
     *
     * @throws IllegalArgumentException if the collection is <code>null</code> or has no elements
     */
    public static void notEmpty(Collection collection)
    {
        notEmpty( collection,
                  "[Assertion failed] - this collection must not be empty: it must contain at least 1 element" );
    }

    /**
     * Assert that a Map has entries; that is, it must not be <code>null</code>
     * and must have at least one entry.
     * <pre class="code">Assert.notEmpty(map, "Map must have entries");</pre>
     *
     * @param map     the map to check
     * @param message the exception message to use if the assertion fails
     *
     * @throws IllegalArgumentException if the map is <code>null</code> or has no entries
     */
    public static void notEmpty(Map map, String message)
    {
        if (CollectionUtils.isEmpty( map ))
        {
            throw new IllegalArgumentException( message );
        }
    }

    /**
     * Assert that a Map has entries; that is, it must not be <code>null</code>
     * and must have at least one entry.
     * <pre class="code">Assert.notEmpty(map);</pre>
     *
     * @param map the map to check
     *
     * @throws IllegalArgumentException if the map is <code>null</code> or has no entries
     */
    public static void notEmpty(Map map)
    {
        notEmpty( map, "[Assertion failed] - this map must not be empty; it must contain at least one entry" );
    }


    /**
     * Assert that the provided object is an instance of the provided class.
     * <pre class="code">Assert.instanceOf(Foo.class, foo);</pre>
     *
     * @param clazz the required class
     * @param obj   the object to check
     *
     * @throws IllegalArgumentException if the object is not an instance of clazz
     * @see Class#isInstance
     */
    public static void isInstanceOf(Class clazz, Object obj)
    {
        isInstanceOf( clazz, obj, "" );
    }

    /**
     * Assert that the provided object is an instance of the provided class.
     * <pre class="code">Assert.instanceOf(Foo.class, foo);</pre>
     *
     * @param clazz   the required class
     * @param obj     the object to check
     * @param message a message which will be prepended to the message produced by
     *                the function itself, and which may be used to provide context. It should
     *                normally end in a ": " or ". " so that the function generate message looks
     *                ok when prepended to it.
     *
     * @throws IllegalArgumentException if the object is not an instance of clazz
     * @see Class#isInstance
     */
    public static void isInstanceOf(Class clazz, Object obj, String message)
    {
        Assert.notNull( clazz, "The clazz to perform the instanceof assertion cannot be null" );
        Assert.isTrue( clazz.isInstance( obj ), message +
                                                "Object of class '" + ( obj != null ? obj.getClass().getName() : "[null]" ) +
                                                "' must be an instance of '" + clazz.getName() + "'" );
    }

    /**
     * Assert that <code>superType.isAssignableFrom(subType)</code> is <code>true</code>.
     * <pre class="code">Assert.isAssignable(Number.class, myClass);</pre>
     *
     * @param superType the super type to check
     * @param subType   the sub type to check
     *
     * @throws IllegalArgumentException if the classes are not assignable
     */
    public static void isAssignable(Class superType, Class subType)
    {
        isAssignable( superType, subType, "" );
    }

    /**
     * Assert that <code>superType.isAssignableFrom(subType)</code> is <code>true</code>.
     * <pre class="code">Assert.isAssignable(Number.class, myClass);</pre>
     *
     * @param superType the super type to check
     * @param subType   the sub type to check
     * @param message   a message which will be prepended to the message produced by
     *                  the function itself, and which may be used to provide context. It should
     *                  normally end in a ": " or ". " so that the function generate message looks
     *                  ok when prepended to it.
     *
     * @throws IllegalArgumentException if the classes are not assignable
     */
    public static void isAssignable(Class superType, Class subType, String message)
    {
        Assert.notNull( superType, "superType cannot be null" );
        Assert.notNull( subType, "subType cannot be null" );
        Assert.isTrue( superType.isAssignableFrom( subType ), message + "Type [" + subType.getName()
                                                              + "] is not assignable to type [" + superType.getName() + "]" );
    }


    /**
     * Assert a boolean expression, throwing <code>IllegalStateException</code>
     * if the test result is <code>false</code>. Call isTrue if you wish to
     * throw IllegalArgumentException on an assertion failure.
     * <pre class="code">Assert.state(id == null, "The id property must not already be initialized");</pre>
     *
     * @param expression a boolean expression
     * @param message    the exception message to use if the assertion fails
     *
     * @throws IllegalStateException if expression is <code>false</code>
     */
    public static void state(boolean expression, String message)
    {
        if (!expression)
        {
            throw new IllegalStateException( message );
        }
    }

    /**
     * Assert a boolean expression, throwing {@link IllegalStateException}
     * if the test result is <code>false</code>.
     * <p>Call {@link #isTrue(boolean)} if you wish to
     * throw {@link IllegalArgumentException} on an assertion failure.
     * <pre class="code">Assert.state(id == null);</pre>
     *
     * @param expression a boolean expression
     *
     * @throws IllegalStateException if the supplied expression is <code>false</code>
     */
    public static void state(boolean expression)
    {
        state( expression, "[Assertion failed] - this state invariant must be true" );
    }

}
